①他奠定了中医治疗学的基础，被后人尊称为“医圣”，他是：____。

②他是北朝的农学家，他的著作反映了南北朝时期民族融合的成果。他是：____。

③他是南朝著名的科学家，在圆周率方面取得了突出的成就。他是：____。

④他是北朝时期杰出的地理学家，写了一部综合性的地理学专著。他是：____。

⑤他是我国古代著名的医学家，在外科手术中使用“麻沸散”，创造“五禽戏”，他是：____。

    There are a number of ways to help improve your memory, so you shouldn't____sad.

    My first way is that if you want to remember something, you have to review it____.You may want to go over the material two days after you have____it, then a week later, then two weeks later, and then a month later. After a month you will find that you can remember the material.

    My second____is to use a colored pen to highlight(用颜色标出) the important parts on your book. This will help you in two ways. First, it will help you focus on the____parts when you learn the knowledge. It is always____than remembering everything.____this will make reviewing better. When you open your book, the color parts will show you the most important things immediately.

    Another good time for remembering information is in the morning because you have just ____the whole night and your brain is fresh and clear. So it's easy to remember the important information in the morning.

在“探究同种物质的质量和体积关系”的实验中，小明对A、B两种物质进行了探究，对实验数据进行了处理，得到了如图的图象．

（1）从所得到的图象来看，同种物质的质量和体积具有 ____关系．

（2）A、B两种物质中，　 ____　物质的密度较大．

单项式﹣ab²的系数是（　　）